Scroll compressors are conventionally incorporated in air conditioners. Having a fixed compression ratio, the scroll compressor is equipped with a power conditioning circuit such as an inverter to control the number of revolutions, thereby controlling the capacity.
However, the provision of the power conditioning circuit brings about a problem of a significant cost increase. Further, the power conditioning circuit consumes a large amount of power and the efficiency decreases due to power loss by the inverter.
In view of the above problem, Japanese Unexamined Patent Publication No. H10-9161 discloses a scroll fluid machine in which a bypass is formed in a stationary scroll so that compressed fluid returns to a low pressure chamber through the bypass.